types of transmission
horizontal & vertical
horizontal transmission
transmission between animals which are not connected foetally
vertical transmission
direct contact (pathogen crosses placental barrier, infecting foetus)
why is external epithelium more susceptible to disease?
trauma & infection
why is mucous membranes more susceptible to disease?
thin walls required for physiological function
how does skin protect from infection/disease?
keratinocytes replicate to general stratified squamous keratinised epithelium
has receptors binding to microbes causing signalling cascade (inflammation triggered)
cells produced during inflammation
cytokines (immunological hormones) chemokines (cell migration factors)
melanocytes
protects skin from uv damage
langerhaan cells
regulates immune system
tissue resistance macrophages present in all layers of epidermis
early warning system for immune system, move quickly to lymph nodes
sebum & sebaceous glands
contains fatty acids (water repellant)
anti-microbial properties
mucociliary escalator
continual movement of cilia in resp. tract
stops colonies forming by moving them continually
the 4 epithelial barriers
physical - skin
physiological - mucous membranes
biochemical - gastric acid
immunological - macrophages
oral cavity/oesophagus epithelial cell type?
stratified squamous epithelium
biochemical barrier of oral cavity/oesophagus?
lysozyme in saliva
paneth cells
specialised secretory epithelial cells in small intestine
produce granules (cryptidins) containing antimicrobial peptides & immunomodulating proteins which regulate composition of intestinal flora
how does the small intestine protect from infection?
contains cryptidins
cryptidins
synthesised by paneth cells fights bacterial & fungal pathogens